Pore size and temperature effects in membrane separation of albumin from immunoglobulins

A series of ethylene-vinyl alcohol co-polymer hollow fiber membranes, differing in maximum pore diameter (0.01, 0.02, 0.03 micron), in modules of 2 m2 total surface area, were evaluated for separation of immunoglobulins G and M (IgG and IgM) from albumin (Alb) in normal human plasma at two different temperatures (4 degrees C and 37 degrees C). Separation was based on molecular size differences. In the dead end mode, with constant flow rate (20 ml/min) filtration, nearly total recovery of Alb, 27% rejection of IgG, and 87% rejection of IgM at VT = 2.4 L (total volume of filtrate accumulated at transmembrane pressure delta p = 300 mmHg) was observed for the largest pore membrane at 37 degrees C. A significant increase in IgG rejection to 50% was observed at 4 degrees C for this membrane, with a concomitant decrease of VT to 1 L. Average rejection coefficients of representative solutes, and delta p dependence on filtrate volume, were analyzed using the log-normal regression method and membrane pore blocking models. Filtration characteristics were noted to be dominated by the native membrane properties at 37 degrees C, and by solute-solute and solute-membrane interactions at 4 degrees C.